THE REACTION OF SUPEROXIDE WITH CARBOHYDRATE SULFONATES

The reaction between methyl di-O-benzyl-4,6-di-O-mesyl-alpha-D-glucopy ranoside (1b) and potassium superoxide resulted in hydrolysis, and gav e methyl 2,3-di-O-benzyl-alpha-D-glucopyranoside (1) as a sole product . When the reaction was performed with a vicinal dimesylate, methyl be nzylidene-2,3-di-O-mesyl-alpha-D-altropyranoside (4b), again the hydro lysis product, methyl 4,6-O-benzylidene-alpha-D-altropyranoside (4) wa s obtained. However, the reaction of potassium superoxide with another vicinal dimesylate, methyl benzylidene-2,3-di-O-mesyl-alpha-D-glucopy ranoside (3b), nucleophilic displacement took place to afford methyl 4 ,6-0-benzylidene-alpha-D-altropyranoside (4). Apparently different res ults from two trans vicinal dimesylates, 3b and 4b are explained by th e transient formation of epoxides, methyl 3-anhydro-4,6-O-benzylidene- alpha-D-allopyranoside (8) and methyl -anhydro-4,6-O-benzylidene-alpha -D-mannopyranoside (9) by KO2. The reaction between the allo epoxide 8 and KO2 gave altro 4. The manno epoxide 9 also afforded altro 4 as th e major product. Facile epoxide formation by the reaction of a vicinal dimesylate and superoxide was also observed with opropylidene-5,6-di- O-mesyl-alpha-D-glucofuranose: 3-O-benzyl-1,2-O-isopropylidene-beta-L- idofuranose was obtained.